A python library for calculating Allan deviation and related time & frequency statistics. GPL v3+ license.
Developed here https://github.com/aewallin/allantools, but also available on PyPi at https://pypi.python.org/pypi/AllanTools
Input data should be evenly spaced observations of either fractional frequency, or phase in seconds. Deviations are calculated for given tau values in seconds.
These statistics are currently included:
- ADEV Allan deviation
- OADEV overlapping Allan deviation,
- MDEV modified Allan deviation,
- TDEV Time deviation
- HDEV Hadamard deviation
- OHDEV overlapping Hadamard deviation
- TOTDEV Total deviation
- MTIE Maximum time interval error
- TIERMS Time interval error RMS
see /tests for tests that compare allantools output to other (e.g. Stable32) programs. More test data, benchmarks, ipython notebooks, and comparisons to known-good algorithms are welcome.
See /docs for documentation in sphinx format. On Ubuntu this requires the 'python-sphinx' and 'python-numpydoc' packages. html documentation using sphinx can be built locally with
make html
this generates html documentation in /docs/_build/html
The sphinx documentation is also auto-generated online
See /examples for some examples in IPython notebook format.
github formats the notebooks into nice web-pages, for example
todo: add here a very short guide on how to get started with ipython
- Anders E.E. Wallin, anders.e.e.wallin "at" gmail.com
- Danny Price, https://github.com/telegraphic
- Cantwell G. Carson, carsonc "at" gmail.com
clone from github, or download from pypi.
sudo python setup.py install
import allantools # https://github.com/aewallin/allantools/
rate = 1/float(data_interval) # data rate in Hz
taus = [1,2,4,8,16] # tau-values in seconds
# fractional frequency data
(taus_used, adev, adeverror, adev_n) = allantools.adev(fract_freqdata, rate, taus)
# phase data
(taus_used, adev, adeverror, adev_n) = allantools.adev_phase(phasedata, rate, taus)
# notes:
# - taus_used may differ from taus, if taus has a non-integer multiples of data_interval
# - adeverror assumes 1/sqrt(adev_n) errorsTo do:
- Stable32-style plots using matplotlib
- Modified Total variance
- Time Total (modified total variance scaled by (t^2/3) )
- Hadamard Total
- Tests for different noise types according to IEEE 1139, include power-spectral-density calculations
- Conversion between phase noise and Allan variance
- The mtie_phase_fast approach to MTIE, using a binary tree (see BREGNI reference)
Make sure your patch does not break any of the tests, and does not significantly reduce the readability of the code.
http://en.wikipedia.org/wiki/Allan_variance
1139-2008 - IEEE Standard Definitions of Physical Quantities for Fundamental Frequency and Time Metrology - Random Instabilities http://dx.doi.org/10.1109/IEEESTD.2008.4797525
S. Stein, Frequency and Time - Their Measurement and Characterization. Precision Frequency Control Vol 2, 1985, pp 191-416. http://tf.boulder.nist.gov/general/pdf/666.pdf
W.J.Riley, "THE CALCULATION OF TIME DOMAIN FREQUENCY STABILITY" http://www.wriley.com/paper1ht.htm
Tom Van Baak http://www.leapsecond.com/tools/adev_lib.c
Fabian Czerwinski, Matlab code http://www.mathworks.com/matlabcentral/fileexchange/26659-allan-v3-0
M. A. Hopcroft, Matlab code http://www.mathworks.com/matlabcentral/fileexchange/26637-allanmodified
SESIA I., GALLEANI L., TAVELLA P., Application of the Dynamic Allan Variance for the Characterization of Space Clock Behavior, http://dx.doi.org/10.1109/TAES.2011.5751232
S. BREGNI, Fast Algorithms for TVAR and MTIE Computation in Characterization of Network Synchronization Performance. http://home.deib.polimi.it/bregni/papers/cscc2001_fastalgo.pdf
David A. Howe, The total deviation approach to long-term characterization of frequency stability, IEEE tr. UFFC vol 47 no 5 (2000) http://dx.doi.org/10.1109/58.869040
Ilaria Sesia and Patrizia Tavella, Estimating the Allan variance in the presence of long periods of missing data and outliers. 2008 Metrologia 45 S134 http://dx.doi.org/10.1088/0026-1394/45/6/S19